Action Statement Flora and Fauna Guarantee Act 1988 No. 136 Alpine Spiny Crayfish Euastacus crassus Description and distribution The Alpine Spiny Crayfish Euastacus crassus Riek 1951 is a small to medium freshwater spiny crayfish with an Occipital – Carapace Length (OCL) of up to 58 mm (Morgan 1997). Members of the genus Euastacus are distinguished by heavy claws or chelae and a spiny appearance (Zeidler 1982). The species is distinguished from the smaller Victorian species by its lack of a male cuticle partition. This partition is a gap between the membrane running from the body onto the underside of the first joint of the fifth walking leg of the male. The membrane does not reach the male genital pore. Females reach sexual maturity at around 30-40 OCL. Specimens usually a deep brown colour, occasionally with red tinges dorsally, with orange thoracic spines and tubercles. The Distribution in Victoria (DSE 2004) underside is orange and green. The Alpine Spiny Crayfish is one of the most localised species in the Euastacus genus and is vegetation at the type localities as dry sclerophyll restricted to the high country occurring in streams forest and heath in largely granite areas with in southern NSW, the ACT and in the eastern semi- abundant ferns along stream banks at one site. He alpine country of Victoria. The range extends form also notes that the species is patchily distributed north-east to south-west approximately 210 km. In in the ACT at sites with relatively undisturbed Victoria, it extends as far as Mount Beauty and vegetation. Mount Hotham at elevations above 1 000 m, which Life history and ecology may be snow covered in winter (Morgan 1997). All While the biology of this species specifically is known sites are located in the Alpine National unknown, in general, mating activity between Park. The most recent records are those of Raadik mature crayfish occurs from May onwards each et al. (2001) who found a total of seven individuals year, following which females carry eggs under the from four sites out of a total of 27 sites surveyed tail. The eggs hatch from October onwards, in the Upper Murray River Basin. depending on seasonal conditions and the species. The dependent juvenile crayfish are carried beneath the tail for some weeks or months after Habitat hatching. Little is known about the habitat of this species except that it occupies cool streams in alpine and sub-alpine areas. Morgan (1997) describes the The yolk of the egg is retained by the young The biology of this species is poorly known, and hatchlings as a yolk sac supplying food during the environmental parameters under which it early growth. Once the yolk sac has been exists are not well understood. The slow growth completely absorbed, the young disperse to fend rate and low fecundity of many Euastacus renders for themselves. them less resilient to reduction in population numbers through habitat destruction and Most species of Euastacus are moderate burrowers, catastrophic events. seeking refuge under rock ledges and amongst submerged, in-stream tree roots (Zeidler 1982). Invertebrate species that have a limited distribution are vulnerable to localised The diet of spiny freshwater crayfish consists environmental perturbations (Williams 1990). primarily of aquatic and semi-aquatic vegetation, Localised catastrophic events, such as an extended benthic invertebrates (Goddard 1988), fungi and drought or wildfire could effect populations of the bacteria found in rotting detrital matter (DCE Alpine Spiny Crayfish by resulting in the loss of all 1992). habitat components. Catastrophic seasonal events Conservation Status that occur irregularly include low flows in drought years, fires, and dust deposition. Following fire, the National conservation status amount of run-off and the peak discharge The Alpine Spiny Crayfish has not been listed increases which leads to great increases in under the Commonwealth Environment Protection sediment load carried by the rivers. Heavy rainfall and Biodiversity Conservation Act 1999. can also lead to increased salinity. Baillie and Groombridge (1996) assessed the Alpine Any activity which damages stream bank integrity Spiny Crayfish against the IUCN criteria. They and alters water tables or stream flow, particularly determined that it was ‘endangered’, based on in smaller streams, could be harmful to the species ‘Extent of occurrence estimated to be less than survival locally (Horwitz 1990). 5 000 km2 or area of occupancy estimated to be The introduction of exotic biota could also be a less than 5 000 km2, and estimates indicating (a) threat due to predation, competition, or the spread severely fragmented population or known to exist of disease (Horwitz 1990). Predation by introduced at no more than five locations; and.…continuing species are thought to have reduced populations of decline, inferred, observed or projected in area, Galaxias species and to have altered the structure extend and/or quality of habitat.’ of invertebrate populations in alpine waters Victorian conservation status (Cullen and Norris 1988). The introduced Brown Trout Salmo trutta, occurs in the Berrima River and The Alpine Spiny Crayfish has been listed as Snowy River system, and predation by this species threatened under the Flora and Fauna Guarantee may have a detrimental impact on populations of Act 1988. the crayfish. Decline and threats Grazing and trampling by cattle can cause stream The Alpine Spiny Crayfish is considered threatened bed and bank degradation, increase in because of its restricted distribution, and relatively sedimentation and turbidity, and increased low abundance within Victoria (Baker 1990, SAC nutrient concentrations in water. 2001), paucity of records and very limited biological information on the species. Perceived Sediment deposition in streams is thought to be threats include habitat loss and modification from detrimental to young crayfish as it coats the natural disasters such as wildfire, cattle trampling, substrata and fills interstitial spaces. These areas altered hydrology and water quality. Predation by may be of value in protecting juvenile crayfish introduced predators may also pose a threat to the from predators. In a recent survey of Gippsland crayfish. Spiny Crayfish habitat, Koster et al. (1999) found that a negative relationship between the presence In its final recommendations the Scientific of South Gippsland Spiny Crayfish and levels of in- Advisory Committee (SAC 2001) determined that stream silt. Increased turbidity can have adverse the Alpine Spiny Crayfish is significantly prone to physical, physiological and behavioural effects on future threats which are likely to result in stream dwelling plants and animals. extinction, and very rare in terms of abundance or distribution. Populations of Alpine Spiny Crayfish may be threatened by over-collection for food or bait. The distribution and abundance of the Alpine Whilst collection of specimens for confirmation of Spiny Crayfish is not well documented. Recent identity may be necessary at new sites, this surveys have recorded the species in low practice should be otherwise avoided. Appropriate abundance and at only a few sites (Raadik 2001). survey techniques include the use of baited traps, in which crayfish can be trapped alive and 2 released, active searching, either at night using a 3. Determine key habitat parameters for the spotlight, or during the day searching amongst in- species as a basis for future management stream woody debris and rocky substrate, and Intended Management Action electro-fishing (the use of electricity to stun fish and macro-invertebrates). The intended management actions listed below are further elaborated in DSE’s Actions for Biodiversity Although National parks are generally less Conservation database. Detailed information about modified than other areas, they can still contain the actions and locations, including priorities, is point sources of pollutants and may be subject to held on this system and will be provided annually to the effects of management practices elsewhere in land managers and other authorities. the catchment (Merrick 1995). Wider Conservation Issues Systematic Surveys 1. Survey the stream-sides in those catchments Thirty- three species of freshwater crayfish species most likely to contain populations of the in Australia are considered rare or threatened Alpine Spiny Crayfish. Surveys will concentrate (Horwitz 1995), mainly due to their confined on unsurveyed streams above about 800 m in geographic distributions (Williams 1990). Few altitude and within the Alpine National Park. recovery plans are available for freshwater crayfish and until recently, the Orbost Spiny Crayfish was Responsibility: DSE (Biodiversity & Natural the only Euastacus listed in Victoria and therefore Resources Division, North East Region), Parks the only species with a recovery plan. Monitoring Victoria the effectiveness of the measures designed for the Habitat protection Alpine Spiny Crayfish may provide guidance for the conservation of other freshwater crayfish 2. Protect Alpine Spiny Crayfish habitat within species. the Alpine National Park by minimising or avoiding the impacts of recreation and park Also occurs with Broad-finned Galaxias Galaxias management activities which might pose a brevipinnis (rare, restricted) and Mountain Galaxias threat to this species or its habitat (eg. Galaxias olidus (insufficiently known). construction or upgrading of roads, tracks and Existing conservation measures visitor facilities, and fire prevention